Refrigerant Receivers

Types: 

• full size receivers - holds entire system charge (has queen valve and king valve)

• Oversized Receiver – holds excess system charge (condenser flooding)

• Partial Receiver – holds a portion of the system charge in the receiver and the rest in condenser

Components

• Inlet - Queen Valve – Full size

• Outlet – king valve – Quill - All receivers

• Liquid level indicators on large receivers (bulls eye)

• Liquid level gauge glass ( ball checks for protection if glass breaks)

Receiver Capacity As Required by B-52

• (4.6.2) most hold the entire refrigerant charge and only occupy 90% of its volume at 90 F

• if refrigerant side head pressure control is used receiver must be oversized by 50 % Formula

- sizing of receivers Cr = Res + 20% / 0.9

cr = capacity of receiver

res = ref. charge in system (lb)                                              

20% = extra ref. charge

• = 90% fill limit of a receiver

example Question: find the size of a receiver required for a system that has a requirement for 83 lbs of refrigerant

Cr = (83 + 20% or 83 lbs + 1.2) / 0.9 = 110.67 lbs ref.

High Pressure Safety

• purpose: a pressure responsive mechanism designed to stop the operation of the compression at predetermined safe pressure

• settings: water cooled 20% above condensing pressure

• settings: air 20% below high side design pressure

Relief Safety Devises

• purpose: a safety mechanism designed to open before dangerous pressure is reached

• usually mounted any place in the system where liquid refrigerant may be isolated by valves

Types

• fusible plug – temperature operated (non resetting)

• rupture disk – pressure operated (non resetting)

• pressure relief – valve pressure operated (resets when pressure drops to safe limit approximate. 10 to 20 % below setting

Approximate. Discharge Settings for PRV 's

• R 22 approximate 300 PSIG

• R 12 approximate 175 PSIG
Capacity of Relief devises
• the minimum required discharge capacity is found using the following formula 
C = fDL

C = minimum discharge capacity lb/air/min

D = outside diam. Of vessel (ft.)

L = length of vessel

f = factor dependant on refrigerant (table 6) Example question: 

Select a PRV for the following Receiver

Receiver 36 “ diam.

Length 5 ft.

Ref. R 12

C = 1.6 x 3 ft. x 5 ft. = 24 lb/air/min